Dont stereotype Silicon Valley. Sales are still sales and depending on the industry vertical or customer accounts, 1) they dress no different than the financial services firms, 2) and bought suits from brooks or bespoke, and 3) flaunt labels just like those in finance.

But if you are just going to be a sales person at Tesla or Apple store, whatevers.

If it hasn't happened, don't wear a cashmere tie. It might be judged as too fancy. Also, monk strap shoes on an interview always will have more potential to harm than to help. Safely deviating from the norm on an interview means looking only slightly outside the norm.